The present invention relates to a device for observing and analyzing the quality of precious stones, especially diamonds, and in particular to a device which provides relevant information regarding a stone""s symmetry, brightness, and efficiency of light return.
While a significant part of a diamond""s value is determined by its weight or carat, the popularity of diamonds as gem stones is due in large part to their inestimable brilliance. The degree of a diamond""s brilliance is influenced significantly by its cut, transparency, clarity, and color.
When diamonds are cut to traditional xe2x80x9cidealxe2x80x9d cut angles and the facets are carefully aligned to facilitate xe2x80x9cmirroring,xe2x80x9d light leakage can be minimized and a greater percentage of light will be returned to the viewer, thereby giving the diamond a brighter appearance. xe2x80x9cMirroringxe2x80x9d refers to the reflection of light to form symmetrical geometric patterns, wherein the facets work together to collect light and return the maximum amount of light to the viewer.
Brightness, however, is a function of several attributes of cutting. Even though light may not be xe2x80x9cleakingxe2x80x9d or passing through the rear side (xe2x80x9cpavilionxe2x80x9d) of the diamond, there is no guarantee that large amounts of light are being returned to the viewer. In order to evaluate the efficiency of light return, light must be gathered from around the viewer, and its reflective pattern analyzed.
Heretofore invented has been a device (see U.S. Pat. No. 4,647,194) which relates to the judging of brilliancy in diamonds by viewing a stone through a magnifying lens wherein the object side of the lens is fitted with a solid red colored disc having a centrally-located hole. Viewing the diamond through the lens assembly provides the viewer with an image of the diamond in which those areas which are reflecting light to the viewer appear as red, whereas those areas of the diamond not reflecting light, but leaking light through the pavilion, appear colorless. This observation allows the viewer to form a general conclusion about the light reflective properties or brilliancy of the particular stone.
The prior art device does not, however, permit the angles of reflective light to be analyzed. Consequently, no information is available regarding the stone""s symmetry or the efficiency of light return based on the cut of the diamond. Without such information, faults in the diamond""s cut may not be apparent, particularly to an inexperienced purchaser. Such faults may significantly impact the appearance of the gem stone and detract from its total value.
It is an object of the present invention to address the aforementioned problem and provide a device with which a viewer may judge a stone""s brightness and symmetry via the observed efficiency of light return from various angles of incidence upon the diamond.
The device of the present invention comprises a simple body wherein a precious stone such as a diamond is placed between a light source and a magnifying lens. The lens is equipped, on the object side, with a multicolored disc wherein each color represents a ring around a portion of the disc, and wherein the stone is viewed through a centrally-located hole in said disc.
Light from the light source is reflected from each colored ring onto the diamond""s surface at an angle defined by the ring""s position from the center of the disc through which the observer views the diamond. Because each angle or range of angles is represented by a specific color, light return efficiency can be analyzed and the symmetry and brightness of the stone evaluated.